NativeBIM / Demos / Energy-ready multifamily bar
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IFC showcase: Energy-ready multifamily bar
A three-storey multifamily bar with space boundaries on the wall faces, gbXML export, an area check per space, and the same spaces read at the wall centre lines.
This model is illustrative. It is built from a script with the dimensions listed under Sources, and it does not represent an existing or as-built building.
3D model
The viewer opens energy-ready-bar.glb, the glTF that NativeBIM writes from the IFC file. The IFC file is energy-ready-bar.ifc.
What is in the model
| Item | Count or value |
|---|---|
| Walls | 377 |
| Doors | 311 |
| Windows | 50 |
| Slabs | 27 |
| Roofs | 2 |
| Spaces | 337 |
| Storeys | 4 |
Requirements
The model does not yet meet every requirement of a building. Each is measured on the model’s geometry by casting rays at it from sample points 1.163 m apart.
| Requirement | What it asks | Result |
|---|---|---|
| Every enclosed area has a floor | Rooms are walked on: an area walls close in at a storey level and nothing to stand on is not a room. | Met |
| The interior is closed in | Walls, doors and windows close every interior floor on all sides; a gap in the walls is a hole in the building. | Not yet: 8 of 5553 samples fail |
| Rain from above is kept off every floor | A roof over every floor, with no gaps between its planes, at its hips and valleys, or where it meets a wall. | Met |
| There is a way in | At least one door in the envelope. | Met |
Drawing set
Draft drawing set generated from the model: energy-ready-bar-drawings.pdf (PDF, 29 sheets).
- G-001 COVER SHEET AND SHEET INDEX
- A-101 LEVEL 1 FLOOR PLAN
- A-102 LEVEL 2 FLOOR PLAN
- A-103 LEVEL 3 FLOOR PLAN
- A-601 DOOR SCHEDULE
- A-602 DOOR SCHEDULE
- A-603 DOOR SCHEDULE
- A-604 DOOR SCHEDULE
- A-605 DOOR SCHEDULE
- A-606 DOOR SCHEDULE
- A-607 DOOR SCHEDULE
- A-608 DOOR, WINDOW AND ROOM FINISH SCHEDULES
- A-609 ROOM FINISH SCHEDULE
- A-610 ROOM FINISH SCHEDULE
- A-611 ROOM FINISH SCHEDULE
- A-612 ROOM FINISH SCHEDULE
- A-613 ROOM FINISH SCHEDULE
- A-614 ROOM FINISH SCHEDULE
- A-615 ROOM FINISH SCHEDULE
- A-616 ROOM FINISH SCHEDULE
- A-617 ROOM FINISH AND AREA SCHEDULES
- A-618 AREA SCHEDULE
- A-619 AREA SCHEDULE
- A-620 AREA SCHEDULE
- A-621 AREA SCHEDULE
- A-622 AREA SCHEDULE
- A-623 AREA SCHEDULE
- A-624 AREA SCHEDULE
- A-625 AREA SCHEDULE
Elevations are not generated yet, so this drawing set has plans and schedules only. Sections are not generated yet, so this drawing set has plans and schedules only.
Energy model geometry, checked
303 spaces, 2727 surfaces and 658 openings. Every space passes the area balance: the surfaces close the volume (largest residual 1.7e-7 m2) and the divergence-theorem volume equals the prism volume. Read at the wall centre lines instead, the spaces add up to +26.3 percent floor area, +17.2 percent wall area and +35.2 percent volume, the envelope area is +27.5 percent, and 54 percent of the internal wall surfaces have no equal partner on the other side.
| Spaces | Count | Boundaries | Area, closure and volume balance | Closed in the gbXML file |
|---|---|---|---|---|
| Dwelling rooms | 288 | 2250 | 288 | 288 |
| Corridors | 3 | 93 | 3 | 3 |
| Stairs | 6 | 60 | 6 | 6 |
| Other spaces | 6 | 324 | 6 | 6 |
| All spaces | 303 | 2727 | 303 | 303 |
| Kind | Count |
|---|---|
| Surfaces (parent boundaries) | 2727 |
| Type A (2a) | 2298 |
| Type B (2b) | 429 |
| Internal type A, each paired with the boundary of the space behind it | 1936 |
| Internal type A with no corresponding boundary | 0 |
| Virtual | 0 |
| Openings, coplanar with their wall or slab | 658 |
| Quantity | Area, m2 |
|---|---|
| External wall surfaces, gross | 2251.8 |
| of which on the curtain wall | 26.9 |
| Windows | 116.1 |
| Curtain wall glass | 20.2 |
| Doors | 85.7 |
| Window-to-wall ratio (windows and curtain wall glass over the gross wall) | 6.1 percent |
| Quantity | Interior faces | Centre lines | Difference | Error |
|---|---|---|---|---|
| Floor area | 3578.1 m2 | 4519.6 m2 | +941.5 m2 | +26.3 percent |
| Wall area (gross) | 11669.3 m2 | 13672.7 m2 | +2003.4 m2 | +17.2 percent |
| Volume | 10724.2 m3 | 14497.2 m3 | +3773.1 m3 | +35.2 percent |
| Envelope area, walls (external) | 2251.8 m2 | 2688.0 m2 | +436.2 m2 | +19.4 percent |
| Envelope area, floor on ground and roof | 2386.0 m2 | 3227.4 m2 | +841.4 m2 | +35.3 percent |
| Envelope area, total | 4637.8 m2 | 5915.3 m2 | +1277.5 m2 | +27.5 percent |
| Spaces | Count | Floor area | Wall area | Volume | Volume, per space |
|---|---|---|---|---|---|
| Dwelling rooms | 288 | +10.3 percent | +12.9 percent | +18.1 percent | +13.8 percent to +47.1 percent |
| Corridors | 3 | +127.3 percent | +83.0 percent | +143.0 percent | +11.7 percent to +402.0 percent |
| Stairs | 6 | +4.9 percent | +9.0 percent | +12.3 percent | +12.0 percent to +12.9 percent |
| Other spaces | 6 | +9.7 percent | +8.3 percent | +17.5 percent | +17.2 percent to +18.1 percent |
| Result | Surfaces | Share of surfaces | Area, m2 |
|---|---|---|---|
| Paired | 548 | 46.1 percent | 4851.2 |
| Overlap a neighbour, ends differ | 612 | 51.5 percent | 6101.4 |
| No surface behind | 28 | 2.4 percent | 548.9 |
| Internal wall surfaces | 1188 | 100 percent | 11501.4 |
Check from the boundaries: for each space the surfaces' area equals the surface area of its prism (largest difference 1.7e-7 m2), the vector sum of area times normal is zero (largest 1.7e-7 m2) and the divergence-theorem volume equals the prism volume (largest difference 6.8e-7 m3). The same three checks, read back from the gbXML text (areas and closure from the Surfaces, volume from each Space's ClosedShell), give 2.4e-5 m2, 1.2e-5 m2 and 2.2e-5 m3. All 1936 internal type A boundaries have a corresponding boundary that faces them and has the same area. 303 spaces are listed with their numbers in area-balance.csv.
Centre-line reading, as measured here: each room polygon is moved out by half the thickness of the wall behind each edge, the floor to the middle of the slab below and the ceiling to the middle of the slab above, and nothing is trimmed. The spaces then tile the footprint with no wall or slab volume between them, and the average space height is 3.2 m instead of 3.0 m. Each space on its own is a closed prism, so the surfaces of one space close the volume; what fails is the match between neighbours: 548 of 1188 internal wall surfaces (46.1 percent of them, 42.2 percent of their area) have a surface on the other side with the same ends and heights.
Openings stay inside their wall surfaces on both sides of the comparison (gross areas). Opening areas are the same in both readings and are not part of the difference.
The gbXML file passes the structure check in packages/core/src/energy/gbxml.js. Validation against the gbXML 7.03 XSD runs in tests/energy/oracle/gbxml_xsd_oracle.py when the schema file is available (its licence does not allow vendoring it).
Sources
Where each dimension comes from. Anything marked as chosen for the sample is an assumption, not a measurement.
- Space boundaries: IfcRelSpaceBoundary2ndLevel, its CorrespondingBoundary and the internal and external boundary types. buildingSMART International, IFC4 ADD2 TC1 documentation (IfcRelSpaceBoundary2ndLevel).
- Output format: gbXML schema 7.03 (Campus, Building, Space, Surface, Opening). gbXML.org, Green Building XML schema version 7.03.
- Building: a double-loaded multifamily bar layout, three storeys, on a 260 ft by 170 ft parcel with 10 ft setbacks, from the multifamily test-fit engine defaults. packages/core/src/generative/testfit/multifamily.js and build_multifamily.js. No real building is represented. Wall and slab thicknesses are the generator's..
- Centre-line comparison: each room polygon moved out by half of its wall's thickness, the floor and ceiling moved to the middle of their slabs, nothing trimmed. showcases/energy-ready-bar/midwall.js. A reading chosen for this comparison, not a measurement of any program..
Built 2026-10-27 with node tools/showcase/build.js energy-ready-bar. Re-running the command gives the same bytes.
Notices
NativeBIM is licensed software. It does not provide design, engineering or other professional services. Outputs are drafts for review by the licensed professional of record.
Sheets are marked NOT FOR CONSTRUCTION by default.
Areas are computed by NativeBIM, not a certified BOMA measurement.
IFC and Industry Foundation Classes are marks of buildingSMART International.
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